JP2010012763A - Method and apparatus for preventing oxidation of molten resin in mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that the oxidation of a molten resin in a cavity is generally prevented by sucking air in the cavity by a vacuum pump to evacuate the cavity to reduce the amount of oxygen, however, since a mold includes a combination of a large number of blocks having many mating surfaces and an air vent for venting air is provided to the cavity, there is a limit in the reduction of pressure due to air venting. <P>SOLUTION: A flow channel 23v capable of feeding a nitrogen gas to the position apart from the cavity 23a of the mating surface of a movable mold 23 and a fixed mold 22, a passage 23w allowing the cavity 23a to communicate with the flow channel 23v and extremely reduced in its cross-sectional area as compared with the flow channel 23v at the point of time when the movable mold 23 touches with the fixed mold 22, and a controller 25 setting and controlling the stop time, moving distance and moving speed of the movable mold 23 are arranged. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for preventing oxidation of molten resin in a mold, and more specifically, just before touching a fixed mold by moving a moving mold and closing the mold. In order to prevent outflow of molten resin in the mold to the minimum when it is temporarily stopped with a gap remaining, or after the gap has been secured Then, it describes the technology in which nitrogen gas is fed into the cavity via the mating surface of the mold.

  Conventionally, as a technique for preventing oxidation of molten resin in a mold and an antioxidant device, as a method for preventing oxidation of molten resin in a cavity, air in the cavity is sucked by a vacuum pump and reduced in pressure. It has been common to prevent oxidation by a method of reducing the amount of oxygen.

  However, the conventional methods for preventing the oxidation of molten resin and the antioxidant in the mold have the following problems.

  That is, the mold is a combination of a large number of blocks, and there are many mating surfaces of the blocks. Further, since the air vent for venting air is provided in the cavity, there is a limit to the pressure reduction by venting. That is, it can be said that the countermeasure is centered on preventing the generation of dust by sucking out the gas generated by the oxidation of the molten resin.

  In the present invention, the nitrogen gas can be fed to a position apart from the cavity 23a of the mating surface by the moving mold 23 and the stationary mold 22, and the mold 23 is closed by moving the mold 23. Immediately before touching the mold 22, it is temporarily stopped in a state in which the gap A is secured, subsequently nitrogen gas is fed, the movable mold 23 is moved again, and finally the fixed mold 22 is touched. Further, the stopping time is 0.01 to 4 seconds, and further, nitrogen gas is sent to a position away from the cavity 23a of the mating surface by the moving mold 23 and the fixed mold 22. The movable mold 23 is closed by moving, and the gap A is secured immediately before the stationary mold 22 is touched, and then moved. Nitrogen gas is fed while slowing the degree, and finally the fixed mold 22 is touched. Further, the gap A is 0.05 to 4 mm. The problem has been solved.

  The present invention also provides a flow path 23v that allows nitrogen gas to be sent to a position separated from the cavity 23a of the mating surface of the movable mold 23 and the fixed mold 22, and the cavity 23a and the flow path 23v. When the moving mold 23 touches the fixed mold 22, the passage 23w having a very small cross-sectional area compared to the flow path 23v and the stop time, moving distance, and moving speed of the moving mold 23 are set. And a controller 25 that can be controlled in a controlled manner. Further, the controller 25 closes when the movable mold 23 moves and immediately before the fixed mold 22 is touched. A can be controlled to 0.05 to 4 mm as A, and when the gap A is temporarily stopped, or after the gap A is secured Nitrogen gas is supplied, and the controller 25 can control the stop time in a state in which the gap A is secured within 0.01 to 4 seconds. The controller 25 can further reduce the moving speed after securing the gap A, and can supply the nitrogen gas while reducing the moving speed. Further, the passage 23w is smoothed by polishing or plating, and the depth of the passage 23w is 0.001 to 0.02 mm. Furthermore, the flow path 23v is connected to an electromagnetic valve 42 through a nitrogen gas pipe 43 so as to be freely opened and closed under the control of the controller 25. Therefore, it was the above-mentioned problems are eliminated.

  As is clear from the above description, the present invention can provide the following effects.

  First, a flow path that allows nitrogen gas to be sent to a position away from the cavity on the mating surface of the moving mold and the stationary mold, and the cavity and the flow path are connected, and the moving mold becomes the fixed mold. At the time of touch, the shape of the molded product is arranged by arranging a passage with a very small cross-sectional area compared to the flow path and a controller that can set and control the stop time, moving distance, and moving speed of the moving mold. Nitrogen gas can be sent reliably between the moving mold and the stationary mold without affecting the resin, resulting in defects such as resin burnt, black spots, yellowing, and spears. It became possible to prevent the cause of. In particular, by providing a passage having a very small cross-sectional area, there is no need to provide a port for supplying nitrogen gas in the cavity, and there is no need to worry about burrs on the molded product or backflow of the molten resin.

  Secondly, the controller can be controlled to 0.05 to 4 mm as a gap immediately before touching the fixed mold by closing the moving mold, and temporarily stops with the gap secured. Nitrogen gas can be sent at an ideal timing considering that nitrogen gas flows out by sending nitrogen gas at the time of making it, or after securing a gap. Moreover, by supplying the nitrogen gas in such a form, the pressure of the nitrogen gas is atmospheric pressure in the cavity, and there is no need to change the air vent or change the molding conditions.

  Thirdly, the controller can control between 0.01 and 4 seconds as a stop time in a state where a gap is secured, and the nitrogen gas is externally supplied by feeding nitrogen gas during the stop time. The nitrogen gas can be sent at the most ideal timing considering that it flows out into the air. Moreover, since the stop time is such a short time, it can be said that there is almost no influence on the cycle time.

  Fourthly, the controller can slow down the movement speed after securing the gap, and considering that nitrogen gas flows out to the outside by sending nitrogen gas while slowing down the movement speed. Nitrogen gas can be sent in an ideal timing form.

  Fifth, the passage was smoothed by polishing or plating, so that nitrogen gas could be fed smoothly.

  Sixth, the passage has a depth of 0.001 to 0.02 mm, so that nitrogen gas can be fed more smoothly. Therefore, it cannot be considered at all that burrs are generated in the molded product.

  Seventh, the flow path is connected to a solenoid valve so that it can be opened and closed freely under the control of the controller via a nitrogen gas pipe, making it possible to feed nitrogen gas as needed. .

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Here, FIG. 1 is a diagram showing an overall arrangement of the present invention, FIG. 2 is a diagram showing a state in which the mold secures a gap, and FIG. 3 is a diagram in which the mold is touched and closed. FIG. 4 is a view showing a state in which nitrogen gas is confined in the cavity in a state where the moving mold is seen, and FIG. 4 is a view of the moving mold viewed from the fixed mold side.

  1, 2, 3, and 4, reference numeral 20 denotes an injection molding machine, which is a plasticizing cylinder 21, a fixed mold 22, a moving mold 23, a moving means 24, and a controller. 25. In FIG. 1, the injection molding machine 20 is shown. However, as long as it is a resin molding machine constituting the molds 22 and 23, other types such as a hollow molding machine and an extrusion molding machine may be used. Absent.

  In this case, the plasticizing cylinder 21 melts and kneads the resin material supplied from a hopper (not shown) by rotating the screw configured in the plasticizing cylinder 21 while heating, and the molten resin Is measured in the tip of the plasticizing cylinder 21 by retreating the screw, and when a predetermined amount of molten resin is stored, the rotation of the screw is stopped and the screw is advanced by the axial drive unit of the screw drive device. The stored molten resin can be injected into the molds 22 and 23.

  On the other hand, the molds 22 and 23 including the fixed mold 22 and the moving mold 23 form the resin supply path 22v and the cavity 23a, so that the molten resin injected from the plasticizing cylinder 21 passes through the resin supply path 22v. It passes through the cavity 23a. In this case, when the molten resin fed into the cavity 23a is cooled and solidified, it is taken out as a molded product.

  And in order to take out as a molded product, the molds 22 and 23 are opened by moving the moving mold 23 in a state where the molded product is solidified by cooling, and the molded product is taken out or dropped from the cavity 23a. It is. Note that the resin hardened by cooling in the resin supply path 22v is also considered so that the fixed mold 22 is separated and dropped by some method.

  In addition, the flow path 23v is connected to a position away from the cavity 23a of the land portion 23b of the moving mold 23 so that nitrogen gas can be supplied to the mating surfaces of the molds 22 and 23. 23, and the flow path 23v is connected to a joint 44 that is a nitrogen gas inlet 44, a nitrogen gas pipe 43, an electromagnetic valve 42 that opens and closes at some timing, and a nitrogen gas pipe 41, and finally Although not specifically shown in FIG. 1, it is possible to supply nitrogen gas by connecting to a nitrogen gas generator. In this case, the hole diameter of the flow path 23v can be 1 to 4 mm.

  In addition, a passage 23w having a very small cross-sectional area is formed in the moving mold 23 when the moving mold 23 touches the fixed mold 22 by connecting the cavity 23a and the channel 23v. Yes. In this case, when the moving mold 23 touches the fixed mold 22, the cross-sectional area is very small compared to the flow path 23v. This means that the nitrogen gas is not touched but some gap A is secured. Including the meaning of sending

  The passage 23w is smoothed by polishing or plating so that nitrogen gas flows smoothly. Further, the passage 23w limits the depth to 0.001 to 0.02 mm in order to prevent the occurrence of burrs during injection. In this case, the depth is most preferably 0.001 to 0.01 mm.

  By the way, in FIG. 1, FIG. 2, FIG. 3, all of the cavity 23a, the flow path 23v, and the passage 23w are formed in the moving mold 23. There is no need, and some or all of them may be formed on one of the fixed mold 22 and the moving mold 23 or on both the fixed mold 22 and the moving mold 23.

  Regarding the nitrogen gas generator, the oxygen gas is separated by the difference in the speed of permeation through the membrane by connecting it to a nitrogen gas cylinder storing nitrogen gas or by passing compressed air through the membrane of the hollow fiber. A separation membrane system that generates nitrogen gas, a PSA system that adsorbs a specific gas under a high pressure, discharges a specific gas under a low pressure, and a gas adsorbent can be considered.

  Further, the moving mold 23 is integrated with a moving means 24. In this case, the moving means 24 moves the moving mold 23, and an electric motor or a hydraulic cylinder can be considered. When the molten resin is fed in a state where the molds 22 and 23 are closed, a mold clamping function for preventing the molds 22 and 23 from opening by the molten resin is formed in or separately from the mold. Have in.

  On the other hand, the controller 25 can send a signal 51 for instructing the moving means 24 to start and end and some speed, and a signal 52 for instructing the opening and closing of the electromagnetic valve 42. It has become. Therefore, by having the position detection function in some form with the function of the clock provided in the controller 25, the speed can be controlled. This means that the speed is converted and stored according to the number of revolutions of the electric motor and the flow rate of the fluid flowing through the hydraulic cylinder, and the position can be obtained from the value in relation to time.

  The method for preventing oxidation of molten resin in the mold and the antioxidant apparatus according to the present invention are configured as described above, and the operation thereof will be described below.

  The general operation of the injection molding machine 20 is as follows. First, when the molds 22 and 23 are touched and closed, the molten resin is injected from the plasticizing cylinder 21 so that the cavity 23a passes through the resin supply path 22v. After that, when the molded product in the cavity 23a is cooled, the molded product is taken out or dropped by opening the molds 22, 23, and the molds 22, 23 are closed again. Will be repeated.

  In the present invention, the moving mold 23 moves while the nitrogen gas can be sent to a position away from the cavity 23a of the mating surface of the moving mold 23 and the fixed mold 22. Immediately before touching the fixed mold 22, temporarily stopped in a state where the gap A is secured, subsequently nitrogen gas is fed, and then the movable mold 23 is moved again, and finally the fixed mold 22 is touched. In the closed state, the molten resin is injected to prevent the molten resin from being oxidized in the dies 22 and 23.

  In this case, the time for stopping the moving mold 23 is set to 0.01 to 4 seconds and controlled. And as time to stop, it is desirable that it is ideally 0.01-2 seconds. This value should be set according to the relationship with the gap A. Naturally, if the gap is narrow, the time for feeding nitrogen gas may be reduced. There is also a problem that the amount of nitrogen gas sent to the tank cannot be secured.

  In another aspect of the present invention, the moving mold 23 can be fed while nitrogen gas can be sent to a position away from the cavity 23a of the mating surface of the moving mold 23 and the stationary mold 22. The nitrogen gas was sent from the state where the clearance A was secured immediately before touching the fixed mold 22 by moving, and then the moving speed was slowed down, and finally the fixed mold 22 was touched and closed. By injecting the molten resin in this state, oxidation of the molten resin in the molds 22 and 23 is prevented. If the content of slowing down the moving speed is specifically described, the distance of the gap A is advanced at a speed of about 0.01 to 4 seconds.

  In this case, the clearance A immediately before the stationary mold 22 is touched by closing the moving mold 23 by moving is controlled to 0.05 to 4 mm. The gap A is ideally 0.1 to 2 mm. By the way, this value can also be applied to the invention described before the present invention. As for the gap A, it can be said that a narrower one is desirable. However, when the molds 22 and 23 are touched, it is necessary to secure a passage 25w having a constant cross-sectional area. The problem of formation arises, and the idea of gap A is necessary.

  Here, in the above-described two inventions, there is a description that the nitrogen gas can be sent to a position away from the cavity 23a of the mating surface by the moving mold 23 and the stationary mold 22, This means that nitrogen gas from a nitrogen gas generator (not specifically shown) is supplied from a nitrogen gas pipe 41, a solenoid valve 42, a nitrogen gas pipe 43, a joint 44, which is a nitrogen gas inlet 44, and a flow path. This means that it can be supplied to the mating surfaces of the dies 22 and 23 via 23v.

  In this way, by sending nitrogen gas from the mating surfaces of the dies 22 and 23 to the cavity 23a via the passage 23w, the nitrogen gas in the cavity 23a is at atmospheric pressure even if the air in the cavity 23a is expelled. Therefore, there is no need to change the air vent or change the molding conditions.

  The present invention relates to a method and an apparatus for preventing oxidation of molten resin in a mold, and more specifically, just before touching a fixed mold by moving a moving mold and closing the mold. This is a technology in which nitrogen gas is sent at a time when the process is temporarily stopped in a state where a gap is secured, or after the gap is secured, and in a mold of various resin molding machines including an injection molding machine. As a result, it has been useful for preventing various types of defects that are seen in the occurrence of resin burns, black spots, yellowing, spears, and the like.

  Diagram showing the overall arrangement of the present invention   A diagram showing a state where the mold has a gap.   Diagram showing the state where nitrogen gas is confined in the cavity with the mold touched and closed   View of moving mold from the fixed mold side

Explanation of symbols

20 ··········································································· Plasticizing cylinder 22
22v: Resin supply path 23: Movement mold (mold)
23a... Cavity 23b... Land portion 23v... Flow path 23w... Passage 24... Moving means 25.・ ・ ・ ・ Nitrogen gas pipe 42 ・ ・ ・ ・ ・ ・ Solenoid valve 43 ・ ・ ・ ・ ・ ・ Nitrogen gas pipe 44 ・ ・ ・ ・ ・ ・ Fitting (nitrogen gas inlet)
51 ... Signal 52 ... Signal A ... Clearance

Claims (11)

  The moving mold (23) moves while allowing nitrogen gas to be sent to a position away from the cavity (23a) of the mating surface by the moving mold (23) and the fixed mold (22). Immediately before touching the fixed mold (22), and temporarily stopped with a gap (A) secured, and subsequently nitrogen gas is fed, and then the movable mold (23) is moved again. The method of preventing oxidation of the molten resin in the mold, characterized by touching the fixed mold (22).   The method for preventing oxidation of a molten resin in a mold according to claim 1, wherein the time for stopping is 0.01 to 4 seconds.   The moving mold (23) moves while allowing nitrogen gas to be sent to a position away from the cavity (23a) of the mating surface by the moving mold (23) and the fixed mold (22). From the state where the gap (A) is secured immediately before touching the fixed mold (22), nitrogen gas is fed while slowing the moving speed, and finally the fixed mold (22) is touched. A method for preventing oxidation of molten resin in a mold.   The method for preventing oxidation of molten resin in a mold according to any one of claims 1 to 3, wherein the gap (A) is 0.05 to 4 mm.   A flow path (23v) that allows nitrogen gas to be sent to a position away from the cavity (23a) of the mating surface of the moving mold (23) and the stationary mold (22), the cavity (23a), and the When the moving mold (23) touches the fixed mold (22) after connecting the flow path (23v), the passage (23w) having a very small cross-sectional area compared to the flow path (23v) and the moving An apparatus for preventing oxidation of molten resin in a mold, wherein a controller (25) capable of setting and controlling a stop time, a movement distance, and a movement speed of the mold (23) is provided.   The controller (25) is closed by moving the movable mold (23), and can be controlled to 0.05 to 4 mm as a gap (A) immediately before touching the fixed mold (22). 6. The mold according to claim 5, wherein nitrogen gas is fed at a point of time when the gap (A) is temporarily stopped in a state where the gap (A) is secured, or after the gap (A) is secured. Anti-oxidation device for molten resin inside.   The controller (25) can be controlled between 0.01 and 4 seconds as a stop time in a state in which the gap (A) is secured, and nitrogen gas is fed during the stop time. The apparatus for preventing oxidation of molten resin in a mold according to claim 6.   The controller (25) can reduce the moving speed after securing the gap (A), and feeds nitrogen gas while reducing the moving speed. Antioxidation device for molten resin in the mold.   The apparatus for preventing oxidation of molten resin in a mold according to any one of claims 5 to 8, wherein the passage (23w) is smoothed by polishing or plating.   The said channel | path (23w) is 0.001-0.02mm in depth, The antioxidant of the molten resin in the metal mold | die of any one of Claim 5 thru | or 9 characterized by the above-mentioned. .   The flow path (23v) is connected to an electromagnetic valve (42) so as to be freely opened and closed by the control of the controller (25) via a nitrogen gas pipe (43). The apparatus for preventing oxidation of a molten resin in a mold according to any one of claims 5 to 10.

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